An optical interleaver is a passive fiber-optic device that is used to interleave two sets of dense wavelength-division multiplexing (DWDM) channels (odd and even channels) into a composite signal stream. For example, an optical interleaver can be configured to receive two multiplexed signals with 100 GHz spacing and interleave them to create a denser DWDM signal with channels spaced 50 GHz apart. An optical interleaver can also function as a deinterleaver by reversing the direction of the signal stream passing through the interleaver.
Optical interleavers have been widely used in DWDM systems and have become an important building block for optical networks with high-data-rate transmission. Optical interleavers are easier to manufacture in some respects compared to other bandpass filtering technologies, such as thin-film filters and arrayed waveguided gratings. However, with the increased demand for smaller and smaller optical interleavers, attempts have been made to also reduce the size of the internal components of the optical interleavers. However, as the sizes of the internal optical components are reduced, the process complexity of the fabrication of the internal components increases and the yield of internal components decreases.